Generally, in a radiation generating apparatus, by applying a high voltage between a cathode and an anode arranged in a radiation tube, an electron which is emitted from the cathode is irradiated to the anode, thereby generating a radiation such as an X-ray or the like. In the radiation generating apparatus like this, in order to assure withstanding voltage performance against the high voltage and to cool the radiation tube, such a structure that the radiation tube and a high-voltage circuit board are enclosed in a container filled with an insulating liquid is used. When the electron emitted from the cathode has entered the anode, since most of the incident energy is converted into a heat, the heat generated in the anode is propagated to the insulating liquid and is radiated into the external atmosphere from the insulating liquid through the housing container.
However, in order to cool the anode by the insulating liquid and radiate the heat generated in the anode to the outside from the insulating liquid through the housing container, it is necessary that the insulating liquid flows and is stirred an the housing container. If the insulating liquid is not stirred, the heat is not sufficiently radiated, so that there is a case of occurrence of a thermal damage of the anode, decomposition/deterioration of the insulating liquid, a deterioration of electronic parts constructing the high-voltage circuit board, or the like. When the decomposition/deterioration of the insulating liquid progresses, there is a case where the withstanding voltage performance of the insulating liquid deteriorates and an electric discharge occurs in use of a long time.
Patent Literature 1 discloses an X-ray generating apparatus having a fan for allowing an insulating oil in which an X-ray tube has been sealed to be circulated in the tube container.